FIG. 39 is an explanatory view showing the display states in the power-on state and in the power-off state of a common conventional display device. As shown in FIG. 39, a display device 101 in the power-on state shows an image in a display region A. A region (frame region B) called a frame or a bezel in the periphery of the display region A does not contribute to image display. In contrast, a display device 102 in the power-off state shows no image in the display region A, and the frame region B still does not contribute to image display.
Such common conventional display devices show only a black or gray screen when they show no image (for example, when they are in the power-off state), so that the devices are useless for users. On the contrary, large-size, difficult-to-move display devices (e.g., digital signage and television receivers) can be mere obstructions for users when they are in the non-display state because they occupy the same space either in the non-display state or in the display state. In other words, such common conventional display devices have their own value only when they are in the display state.
In order to solve this disadvantage, a mirror display is proposed which includes a half mirror plate in front of a display device so that it can serve as a mirror when the display is in the non-display state (for example, see Patent Literature documents 1 to 4). Such a mirror display can serve not only as a display, which is the original purpose, but also as a mirror. Specifically, when display light is emitted from the display device, the mirror display shows an image owing to the display light in a region where the display light is emitted from the display device. When no display light is emitted from the display device, on the other hand, the mirror display reflects the outside light and serves as a mirror in a region where the display light is not emitted from the display device.
If a mirror region which serves as a mirror surface in a mirror mode of such a mirror display partially includes a frame region, the mirror region in the mirror mode can have a larger area than a display region in a display mode. Thus, the frame region can effectively be used to improve the utility as a mirror. Further, mirror displays whose frame region can also serve as a mirror may have better design quality in the display mode.